Method of producing patterns, molds, and related products

ABSTRACT

An additive manufacturing method includes removing material from a sheet to create a plurality of individual layer segments formed, placing at least two first layer segments adjacent to each other at the same height to form a first layer having a hollow interior, the at least two first layer segments defining a first portion of an exterior of a part, and placing at least one second layer segment above the at least two first layer segments to form a second layer having a hollow interior, the at least one second layer segment defining a second portion of the exterior of the part. The method includes attaching the first layer to the second layer and removing material from the first layer and from the second layer to form the part having a continuous surface that extends along the first layer and the second layer.

TECHNICAL FIELD

Aspects of the present disclosure relate to apparatus and methods forfabricating components. In some instances, aspects of the presentdisclosure relate to a method for fabricating components (e.g.,patterns, molds, and/or similar products) via techniques or processessimilar to 3D printing manufacturing processes of layering, howeverusing lower cost fill materials without the use of a 3D printer.

BACKGROUND

Additive manufacturing techniques and processes involve the buildup ofone or more materials to make a net or near net shape (NNS) object, incontrast to subtractive manufacturing methods. Although “additivemanufacturing” is an industry standard term (ASTM F2792), additivemanufacturing encompasses various manufacturing and prototypingtechniques known under a variety of names, including freeformfabrication, 3D printing, rapid prototyping/tooling, etc. Newer additivemanufacturing techniques use large-scale 3D printers that are capable offabricating very large parts, molds, patterns, etc. These items can beproduced from fiber-reinforced thermoplastic materials. One method ofproducing these items utilizes a polymer extruder which generates a beadof molten thermoplastic material which is added to the part beingproduced one layer at a time. These layers may be modified and orflattened into wider beads during this additive process using devicessuch as tamping plates, rollers or the like. Using this approach,referred to as 3D printing or additive manufacturing, the part is madeslightly larger than the desired final part. After the part cools andhardens, it is machined to the final size and shape. The part, afterbeing machined, can be formed as a shell of a particular thickness, andhaving a desired size and shape.

While above-described processes may be useful, they can also introduceissues that limit their applicability in certain circumstances. Forexample, the thermoplastic material can shrink as it cools from printingtemperatures to ambient or room temperature. This shrinkage willgenerally not be the same in every direction and in, at least somecases, should be taken into account when developing the geometry of theprinted part, complicating the design and manufacturing processes. Also,since the material as printed is soft and affected by gravity, there isa limit to the maximum angle a wall of the part can be printed. Thus,making a hollow part with a solid top can require either a printedinternal support structure, which increases cost, or other types ofadded support structure for use during printing, which furthercomplicates the manufacturing operation. Also, the materials andequipment commonly used in this process are expensive, limiting thenumber of suitable applications.

An exemplary fill material used in some thermoplastic additivemanufacturing processes is carbon fiber. This material, which can beadded to a base polymer, tends to stiffen and strengthen the underlyingpolymer and also tends to minimize warping that can otherwise occur asthe part cools. Carbon fiber however, can be costly and thereforeincreases the cost of the products produced using this process. Thisincreased cost can limit potential uses to those applications where thevalue of the piece being produced can justify the cost. Lower costreinforcement materials, such as wood fiber, may be unsuitable for usewith at least some manufacturing devices. For at least some parts orbase materials, there can be a maximum amount of fill material that canbe added to a base material (e.g., thermoplastic material). If thismaximum amount of fill material is exceeded, the resulting changes inthe characteristics of the material may adversely affect the ability toprocess the filled thermoplastic material with additive manufacturingsystems, such as 3D printing devices. Even when 3D printing devices orother additive manufacturing systems are able to use highly-filledmaterials, this equipment can introduce high cost, rendering productionof such parts impractical.

SUMMARY

Aspects of the present disclosure relate to, for example, methods andapparatus for fabricating components via layering techniques. Each ofthe aspects disclosed herein may include one or more of the featuresdescribed in connection with any of the other disclosed aspects. Someaspects of the present disclosure are useful for processes of creatingpatterns, molds, and other articles or products using a layering method.In some aspects, this layering method may be comparable to 3D printingor other additive manufacturing methods, while using a technologicalapproach that, in at least some circumstances, can be used withrelatively lower cost fill materials. Some aspects of the presentdisclosure may address issues discussed above, and/or other issues inthe art.

In one aspect, an additive manufacturing method may include removingmaterial from a sheet to create a plurality of individual layer segmentsformed, placing at least two first layer segments adjacent to each otherat the same height to form a first layer having a hollow interior, theat least two first layer segments defining a first portion of anexterior of a part, and placing at least one second layer segment abovethe at least two first layer segments to form a second layer having ahollow interior, the at least one second layer segment defining a secondportion of the exterior of the part. The method may include attachingthe first layer to the second layer and removing material from the firstlayer and from the second layer to form the part having a continuoussurface that extends along the first layer and the second layer.

In another aspect, a method for manufacturing a part may includeremoving a porous material from a sheet to create a plurality ofindividual layer segments, with a CNC router, forming a plurality oflayers with the individual layer segments, and securing the layerstogether to form a part with a shape having a hollow interior. Themethod may include infusing the porous material of the part with acatalyzed thermoset material that is compatible with the porosity of theporous material by using a vacuum pump, by applying pressure, by dippingthe part into the thermoset material, or by spraying the part with thethermoset material and removing material from an exterior of the part,with the CNC router, to form a part having a continuous surface and ahollow interior.

In some aspects, a part is manufactured with a layering process that mayfacilitate the production of a polymer-based product which has arelatively high quantity of low-cost fill material, particularly incomparison to the polymer content of the product. This process may alsoinvolve the use of equipment that is relatively lower cost, particularlywhen compared to extrusion-based thermoplastic additive manufacturingprocesses.

In some aspects, the processes and apparatus described herein may employfiller material to produce a part structure. A polymer material may beadded to the filler material (or materials) which form the majority ofthe finished part (e.g., greater than 75%, by volume and/or by weight),as opposed to processes where filler materials are instead added to apolymer that forms the majority of the finished part. For example, thisprocess can include producing a part structure from the filler materialitself, and, if necessary, trimming the filler material. This fillermaterial may subsequently be infused with a catalyzed thermoset polymerby supplying thermoset polymer, in liquid form, to the filler material.The thermoset polymer, or other suitable material, may harden afterbeing supplied in liquid form. The hardened filler and polymer compositemay impart improved physical properties to the part.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary aspects of the presentdisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 is a perspective view of an exemplary CNC machine operable torout layers of filler materials, according to an aspect of the presentdisclosure;

FIG. 2 is a top view of an exemplary bottom or first layer assembledwith a portion of a second layer of an exemplary product;

FIG. 3 is a top view of an exemplary portion of a layer of a part, withan identifier (e.g., a number and letter) routed into the material ofthe portion of the part;

FIG. 4A is a top view of an exemplary second layer assembled and alignedwith the first layer;

FIG. 4B is an exploded view of the exemplary first and second layersshown in FIG. 4A;

FIG. 5A is a top view of an exemplary near net shape part in a fullyassembled state;

FIG. 5B is a front view of the part shown in FIG. 5A;

FIG. 6A is a perspective view of an exemplary part after being machinedto a desired shape and size;

FIG. 6B is a front view of the exemplary part of FIG. 6A;

FIG. 7 is a partially-schematic view of an exemplary part and aninternal support; and

FIG. 8 is a perspective view of a part with a sealed bottom duringapplication of resin.

DETAILED DESCRIPTION

The present disclosure is drawn to, among other things, methods andapparatus for fabricating components via layering techniques.Specifically, the methods and apparatus described herein may be directedto processes of creating patterns, molds, and other parts or productsusing a layering method.

As shown in FIG. 1, a manufacturing machine, such as a CNC router 11,may be configured to remove material in a controllable manner from aworkpiece. CNC router 11 may be part of a manufacturing systemincluding, for example, a control unit or controller 100 configured togenerate commands to operate a plurality of servomotors and positon atool of CNC router 11. CNC router 11 may be operable to remove materialfrom a variety of different materials. For example, CNC router 11 may beconfigured to position and operate a cutting tool in response to issuesgenerated by controller 100. CNC router 11 may be any suitable machinefor modifying a surface of material, including removing material with acutting tool, such as a 3-axis router (e.g., an apparatus configured thecutting tool with three degrees of freedom), a 5-axis router (e.g., anapparatus configured to position the cutting tool with five degrees offreedom), or an additive manufacturing apparatus having a printing headin addition to a milling head.

An exemplary part manufactured by the process described herein may beformed with an at least partially porous material. An exemplary suitablematerial may include medium density fiberboard (MDF). Individualportions for the part may include Plexiglas, ultra high molecular weight(UHMW) plastic (e.g., UHMW polyethylene), polyvinyl chloride (PVC),plastic, plywood, drywall, aluminum, instead of or in addition to MDF.

The structure of the part may be formed by assembling a plurality oflayers. Each layer may include one or more segments 13. For example, aplurality of layers may be stacked on top of one another to create adesired shape, as described below. In the exemplary configurationillustrated in FIGS. 2-8, the part, when assembled, may have the shapeof a hollow cone. The actual geometric shape of a typical part whichcould be fabricated using this process could vary widely in both shapeand size. For clarity, a cone shape is described herein. However, it isexpected that parts produced using the methods disclosed herein would besignificantly more complex than a simple cone. In this example, eachlayer may include or consist of a bead of a particular desired thicknessand width so that the final structure will resemble structures commonlyproduced using current thermoplastic additive manufacturing techniques.

A process for manufacturing a part may include producing a plurality ofindividual pieces or segments 13 that are subsequently assembled to eachother. For example, each layer, including a bead of a predetermined orknown width, may be formed from segments 13 cut from a sheet 12 ofappropriate material, such as MDF, LDF, or rigid plastic foam. As shownin FIG. 1, segments 13 for a single part may be initially formed in aplurality of sheets 12. The cutting or machining of sheet 12 may beperformed with a suitable machine, such as a CNC router 11, as shown inFIG. 1. CNC router 11 may split or separate individual segments 13 fromeach other, with a plurality of these segments 13 belonging to the samelayer. In the example shown in FIG. 1, each segment 13 may form an open(e.g., semi-circular or arc-shaped) structure. Additionally oralternatively, one or more segments 13 may be sized and shaped for useto form an entire layer, and thus may for a single closed-loop structure(e.g., a closed circle, ellipse, square, rectangle, irregular shape,etc.). Additionally, as shown in FIG. 1, one or more of the segments 13may be nested (e.g., positioned within each other), as the final partmay be formed with a hollow interior, as described below. Nesting aplurality of segments 13 in a single sheet 12 of material may improvematerial yield and reduce cost.

As shown in FIG. 2, a plurality of the individual pieces 13 formed byremoving material from sheet 12, may be secured together to form a layerof a part, such as a portion of a cone. A seam or joint 14 may be formedat the interface between a pair of opposing individual segments 13. Inthe exemplary assembly illustrated in FIG. 2, an upper or second layer15 including a piece 13 is contiguous with and supported on top of aplurality of pieces 13 of a lower or first layer 16. In some aspects, ajoint 14 may be formed by the interface at which individual beads of asingle layer butt together. In some aspects, each joint 14 may be offsetfrom joints 14 formed in adjacent layers (layers immediately aboveand/or immediately below). This offset, or staggering, may improve thestrength of the part.

In the exemplary configuration illustrated in FIG. 2, joints 14 in firstlayer 16 may be circumferentially spaced from each other by 180 degrees,as two arc-shaped segments 13 are assembled together. However, spacingsof 120 degrees, 90 degrees, or irregular spacing, depending on thenumber and shape of segments 13, may also be employed. Each joint 14 ofa first layer (e.g., layer 16) may be offset from each joint 14 of asecond layer (e.g., layer 15) such that, joints 14 of a given layer donot overlap any joint 14 formed by an adjoining layer. In the exampleshown in FIG. 2, joints 14 are formed by butt joints between segments13. Each butt joint 14 of first layer 16 may be offset from one or morebutt joints 14 of second layer 15 (a position where a butt joint 14 willbe formed with second layer 15 is completed being shown in FIG. 2) by 90degrees.

Segments 13 may be employed to manufacture a relatively large structuresuch that a finalized part, described below, may be larger than CNCrouter 11. As the formation of large structures may involve theproduction of a multitude of parts (e.g., segments 13), it may bedesirable to facilitate identification and assembly of these segments13. For example, CNC router 11 or another suitable machining system mayetch or otherwise form a mark 17 on a surface of each segment 13. Eachmark 17 may be indicative of a layer number (e.g., 1, 2, 3, 4, etc.)and/or location within the particular layer (e.g., A, B, C, left, right,top, bottom, etc.) of the segment 13, as shown in FIG. 3. In someaspects, by removing material from each segment 13 to form a mark 17, itmay be possible to identify segments 13 without the need to apply, andsubsequently remove, a label that can interfere with assembly.

As shown in FIGS. 3, 4A, and 4B, one or more segments 13 may includefeatures configured to facilitate assembly of segments 13 into a nearnet shape part. For example, dowel holes 18 may be machined or otherwiseformed in each layer (e.g., one or more segments 13 of each layer) tofacilitate alignment of these layers with respect to each other. Asshown in FIG. 4B, each dowel hole 18 may extend through respective upperand lower surfaces of a particular segment 13. Dowel holes 18 may beused to align each layer with the layer above and/or below. Mechanicalfasteners, such as dowel pins 19, may be inserted into two or morealigned dowel holes 18, as shown in FIG. 4B. Dowel pins 19 and dowelholes 18 may be configured to facilitate permanent assembly orattachment of a plurality of layers, each layer including one or moresegments 13. Each layer may be assembled and permanently attached to oneor more other layers using adhesive, bonding agents, mechanicalfasteners, or a combination thereof. When mechanical fasteners are used,the layers are not required to be compatible with adhesive bondingtechniques. Thus, when mechanical fasteners are used, an entirety of thepart may be free of adhesive.

FIGS. 5A and 5B illustrate a near net shape part or object 20 when eachof the plurality of layers are assembled and attached to each other.Object 20, once assembled, may have a hollow interior formed by theinner radial surfaces of arc-shaped segments 13 (FIGS. 1-4A). Anexterior of object 20 may, once assembled, have a stepped shape. Object20 may, as a whole, may form a conical or frusto-conical shape.

FIGS. 6A and 6B show an exemplary part or cone mold 21 formed byprocessing near net shape object 20. Cone mold 21 may be formed bymachining an outer surface of part or object 20 to a desired final sizeand shape, such as cone mold 21. In some aspects, this machining may beperformed by a CNC machine, such as router 11. Router 11 may, inresponse to commands generated by controller 100, remove material froman exterior surface of object 20 so as to form a continuous surface 30that extends along at least first layer 16 and second layer 15. As shownin FIGS. 6A and 6B, this machined surface 30 may extend from the bottomend of mold 21 to the top end of cone mold 21. As also shown in FIGS. 6Aand 6B, an interior of cone mold 21, which is not machined to form asmooth surface, may retain a stepped surface formed by segments 13 ofeach layer, including layers 15 and 16. Cone mold 21 (or any other partformed by the process described herein) may be larger than CNC router11. For example, mold 21 may have a height that is larger than a heightof CNC router 11, a length larger than a length of CNC router 11, awidth larger than a width of CNC 11, or any combination thereof. Byforming such a large part with a hollow interior, it may be possible tosignificantly reduce the amount of material required to make such apart.

With reference to FIG. 7, a process for manufacturing a part, such as acone mold 21 or other mold, may include producing and including asupport structure, such as support 22. Support 22 may have a shape thatat least partially matches a shape of and interior of cone mold 21.Support 22 may, for example, have a stepped exterior shape that matchesa stepped shape of the hollow interior of cone mold 21. Each step maycorrespond to a respective layer of mold 21, such as layers 15 and 16.

One or more internal supports 22 may be added to the interior of conemold 21 to provide mechanical support to the structure of cone mold 21.This mechanical support may be beneficial during use of mold 21 during amolding process. However, support 22 may be placed within mold 21 priorto the machining of surface 30, if desired. Support 22 may be formed ofa suitable material, such as wood. Support 22 may be temporarily orpermanently attached to mold 21 using adhesive, bonding agents,mechanical fasteners, or a combination thereof. While a single support22 may be secured to an interior of mold 21, a plurality of supports 22may be fabricated and attached to mold 21.

Machined mold 21, with or without support 22, may be suitable forvarious applications. For example, mold 21, or other structuresmanufactured according to aspects of the present disclosure, may be usedas a mold for forming components with fiberglass. Mold 21 may also beuseful as a part for a CNC router, such as a fixture for securingplastic molded parts as they are machined with CNC router 11. Variousporous reinforcement materials may be suitable for this approach, suchas MDF 12, despite these materials having less strength, durability, andwear resistance as compared to traditional materials. In order to usemold 21 in one or more of the above-described applications, it may bedesirable to improve the physical characteristics of mold 21. Forexample, if a majority (e.g., greater than 50%, greater than 75%, orgreater than 90%, by volume and/or by weight) of the material of mold 21is a porous material, such as MDF 12, the inherent porosity of thematerial may be utilized to improve physical properties of the finalproduct.

For example, it may be desirable to apply a reinforcing material to mold21. A process of manufacturing mold 21 may include performing one ormore steps for reinforcing mold 21, including applying a vacuum with theuse of a vacuum pump 24 to the inside of the part, as shown in FIG. 8.Other methods for reinforcing mold 21 may include applying pressure todrive reinforcing material (e.g., catalyzed thermoset material) into themold 21, by dipping the mold 21 into thermoset material, by spraying themold 21 with thermoset material, etc. When pump 24 is so applied to mold21 or another part, air may leak through the part, across the entiresurface of the part, (e.g., due to the width of the bead or layer usedin this process) and when the thickness of the part's outside wall issufficiently thin.

In order to effectively apply reinforcing material via vacuum 24 toreinforce a part such as mold 21, a base or bottom surface 23 of thepart that opposes a narrowed portion or end of mold 21 may be sealed anda high-flow vacuum pump 24 may be connected to part 21 via surface 23.Vacuum pump 24 may be attached to part 21 and used to evacuate air frominside the sealed part 21, as shown in FIG. 8. The volume of airexhausted by the vacuum pump 24 may, in at least some applications, begreater than the volume of air flowing through the surface of thefabricated part so that a level of vacuum, and the resulting air flowthrough the part surface, can be maintained, despite air leaking throughthe surface.

With vacuum pump 24 so attached and operated to actively remove air froman interior of mold 21, a thin, low-viscosity catalyzed resin 25, suchas epoxy, may be applied to the surface of the part, e.g., surface 30,as shown in FIG. 8. The vacuum applied to the interior of the part andthe resulting air flow through the part (e.g., from an outside of thepart, through surface 30, to an interior of the part) may pull or drawliquid resin 25 into the structure of the material. As the resin 25 ispulled into the pores of the material, air flow may be gradually reducedin areas where all or nearly all of the thickness has been infused withresin 25. This may have the effect of increasing air flow in areas wherethe part is not yet fully infused with resin 25. By applying material inthese areas, the entire part 21 may eventually become infused withcatalyzed resin 25. Once an entirety of part 21 is infused with resin25, vacuum pump 24 may be deactivated and resin 25 allowed to fully cureand harden. As a result, the strength and physical properties of part 21may be improved.

In an alternative process, layers of part 21 may be temporarily fastenedtogether with dowel pins 19 or another appropriate method to form a nearnet shape. Then, a seal may be applied to the bottom surface 23 of part21. A vacuum may then be applied by vacuum pump 24 to part 21, resultingin an air flow through the part from the outside of the part 21 to aninterior of the part. A layer of resin 25 may then be applied to thepart 21. As resin 25 is pulled into part 21, resin 25 may gradually sealthose areas, causing vacuum to increase in other areas of part 21,pulling resin 25 in to these unsealed areas. Once part 21 has been fullyinfused in the resin 25 and resin 25 has been allowed to fully cure,resin 25 will have created the bond that holds the layers togetherpermanently. This infusion of resin 25 may occur prior to machining,such as when object 20 has a shape corresponding to FIGS. 5A and 5B.Object 20, once infused with resin 25, may be machined to a desiredfinal size and shape, and used for a wide variety of applications. Oneexemplary application for a mold 21 formed in this manner may be for usein an autoclave. Autoclave use may be suitable as all layers of mold 21may be permanently bonded together by resin 25.

As an alternate to using vacuum to infuse resin into the assembledstructure, a liquid thermoset material may be used. A suitable liquidthermoset material may be sufficiently thin to penetrate the open poresof the material forming the structure of mold 21 through capillaryaction wherein the liquid thermoset material soaks into the structure ofmold 21. This capillary action may be sufficient to infuse resin withoutthe need for additional force, such as vacuum or pressure.

As an alternate to using vacuum to infuse resin into the assembledstructure, it is also possible to use a liquid thermoset material thatis thin enough to penetrate the open pores of the particular structurematerial being utilized through natural capillary action wherein theliquid material soaks into the structure sufficiently without the needfor additional external force such as vacuum or pressure.

Different resin 25 formulations may be combined with differentsubstrates (e.g., material of sheets 12) to achieve desired properties.When an object is formed according to one of the above-describedembodiments, it may be possible to select a particular resin formulationand/or substrate material to arrive at desired physical propertiesuseful for one or more particular applications of the finished partformed by assembling and modifying this object. The resulting part 21may be a lower cost, highly filled, polymer part with many desirableproperties.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentdisclosure which come within the province of those persons havingordinary skill in the art to which the aforementioned disclosurepertains. However, it is intended that all such variations not departingfrom the spirit of the disclosure be considered as within the scopethereof as limited by the appended claims.

1.-20. (canceled)
 21. An additive manufacturing method, the methodcomprising: removing a plurality of separate segments from one or moresheets of material, the segments including a first segment for a firstlayer and a second segment for a second layer; forming an alignmentmechanism on the first layer or the second layer; placing the secondlayer on the first layer using the alignment mechanism to align thefirst layer and the second layer; applying a liquid to the first layerand to the second layer; and allowing the liquid to solidify andpermanently join the first layer and the second layer.
 22. The additivemanufacturing method of claim 21, wherein, once the second layer isplaced on the first layer, the second layer partially overlaps the firstlayer.
 23. The additive manufacturing method of claim 22, wherein thealignment mechanism includes a pin in one of the first and second layersthat is received within a hole in the other of the first and secondlayers.
 24. The additive manufacturing method of claim 23, wherein thesecond layer is secured above the first layer, and the pin extendsvertically from the first layer to the hole, the hole being in thesecond layer.
 25. The additive manufacturing method of claim 21, whereinthe first layer includes a plurality of the segments and the secondlayer includes a plurality of the segments.
 26. The additivemanufacturing method of claim 25, wherein the second segment overlapsthe plurality of segments of the first layer.
 27. The additivemanufacturing method of claim 21, wherein the material is porous. 28.The additive manufacturing method of claim 21, wherein the liquid isapplied outside of a mold.
 29. The additive manufacturing method ofclaim 21, wherein the liquid is a liquid resin.
 30. The additivemanufacturing method of claim 21, wherein the liquid is applied withoutapplying pressure to the first layer and the second layer.
 31. Theadditive manufacturing method of claim 21, wherein the solidified liquidpermanently bonds the first layer to the second layer while thealignment mechanism connects the first layer and the second layer. 32.An additive manufacturing method, the method comprising: forming aplurality of individual segments from a single sheet of material, thesegments including a first segment for a first layer and a secondsegment for a second layer; placing the second segment on the firstsegment; securing the second segment to the first segment; andintroducing a liquid resin to the second segment and the first segmentwhile the second segment is secured to the first segment.
 33. Theadditive manufacturing method of claim 32, further including a pinconnected to the first segment, the pin extending through a hole formedwithin the second segment.
 34. The additive manufacturing method ofclaim 33, wherein the pin comprises a dowel.
 35. The additivemanufacturing method of claim 32, wherein the material is a porousmaterial and introducing the liquid resin causes liquid resin to enterpores of the first segment and the second segment.
 36. The additivemanufacturing method of claim 32, wherein the second segment partiallyoverlaps the first segment after the second segment is secured to thefirst segment.
 37. The additive manufacturing method of claim 32,wherein the liquid resin is introduced with a vacuum pump.
 38. Anadditive manufacturing method, the method comprising: forming aplurality of individual segments including a first segment for a firstlayer and a second segment for a second layer; connecting the secondsegment to an upper surface of the first segment; and introducing asolidifying liquid to the second segment and the first segment while thesecond segment is connected to the first segment outside of a mold. 39.The method of claim 38, wherein the second layer includes a hole forreceiving a fastener connected to the first layer, and a pin extendingfrom a surface of the second layer.
 40. The method of claim 39, whereinthe first layer includes a plurality of first segments located adjacentto each other horizontally and a width measured horizontally, the pinbeing positioned outside of the width of the first layer.